Yeah, but... ~/$ python3 Python 3.6.3 (default, Oct 4 2017, 06:09:05) [GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] on darwin Ty

Yeah, but... ~/$ python3 Python 3.6.3 (default, Oct 4 2017, 06:09:05) [GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import fib >>> fib.fib_tail_recurse(1000) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/Users/kerkeslager/fib.py", line 4, in fib_tail_recurse return fib_tail_recurse(n, i+1, cur_sum+prev_sum, cur_sum) File "/Users/kerkeslager/fib.py", line 4, in fib_tail_recurse return fib_tail_recurse(n, i+1, cur_sum+prev_sum, cur_sum) File "/Users/kerkeslager/fib.py", line 4, in fib_tail_recurse return fib_tail_recurse(n, i+1, cur_sum+prev_sum, cur_sum) [Previous line repeated 994 more times] File "/Users/kerkeslager/fib.py", line 2, in fib_tail_recurse if i >= n: RecursionError: maximum recursion depth exceeded in comparison >>> This is a perfect example of why tail recursion isn't actually very useful.